JPH0371151A - Disconnectable high voltage connector - Google Patents

Abstract

PURPOSE: To decrease both of changes in charges in the initial life and powdering in the initial life by stirring a mixture of carrier particles and precontrolling particles containing a polymer binder and a charge controlling agent which controls the electrification level so as to accelerate the contact state among these particles. CONSTITUTION: The precontrolled particles are produced by dispersing a charging agent in a polymer binder. Then, the mixture is pulverized into a specified particle size to obtain a powder which can be easily fluidized. These precontrolling particles are only mixed with carrier particles in an amt. enough to make the surface area of the carrier particles max. This amt. depends on the relative dimensions and densities of the precontrolling particles and the carrier particles, and it is preferable that the proportion of the precontrolling particles is 10 to 13wt.% of the mixture. After stirring, substantially all of the precontrolling particles are separated from the carrier particles by a convenient means and discarded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] This invention relates to the treatment of carrier particles to make them more suitable for initial use in dry electrophotographic developers comprising carrier particles and electrophotographic toner particles. Regarding. More specifically, this invention relates to a method for preconditioning carrier particles to eliminate or minimize undesirable properties that may cause a photographic developer to exhibit during the initial cycles of its use in an electrophotographic development process. Regarding.

[Conventional technology]

In electrostatography, the electrostatic potential (also called electrostatic latent image)
pattern is formed on the insulating surface by any of a variety of methods. (1) (2) or dielectrically (i.e., electrostatic charges at the dielectric surface may be formed (by direct electrical generation of electron everterns). Typically, an electrophotographic developer is also contacted with the electrostatic latent image to develop the latent image into a toner image.

If desired, the latent image can be transferred to another surface before development.

A well-known type of electrophotographic developer comprises a dry mixture of toner particles and carrier particles.

This type of developer is commonly used in well-known electrophotographic development such as cascade development and magnetic brush development. Particles of such developer are made such that the toner particles and carrier particles occupy separate positions on the triboelectric continuum, so that when they are mixed and come into contact with each other to form the developer. When the toner particles take on a certain polarity and the carrier particles take on the opposite polarity, they become triboelectrically charged. These opposing charges attract each other so that the toner particles stick to the surface of the carrier particles. When this developer is placed in contact with the electrostatic latent image, the electrostatic forces of the latent image (often in combination with an additional applied electric field) attract the toner particles, which are then pulled away from the carrier particles. It adheres electrostatically and imagewise to the surface bearing the latent image. The resulting toner image can then be fixed in place by heating or other known methods (depending on the nature of the surface and toner image) or transferred to another surface where it can be similarly can be fixed to.

A number of requirements are implied in such development systems. That is, the electrostatic force between the toner and carrier particles is strong enough to keep the toner particles held on the surface of the carrier particles while developer is transferred to and in contact with the latent image. When the next contact occurs, the electrostatic attraction between the toner particles and the latent image causes the toner particles to be pulled away from the carrier particles and deposited in the required amount on the surface bearing the latent image. It must be of suitable strength.

In order for these requirements to be met for proper development, (3) (4) the electrostatic charge levels of the toner particles and carrier particles must be maintained within appropriate ranges.

The toner particles of dry developers often contain substances called charge agents or charge control agents that help settle and maintain the charge within acceptable limits.

Many types of charge control agents have been used and are described in the published patent literature. However, the level of charge that can be created and maintained on toner particles is still highly dependent on the nature and condition of the carrier particles.

Newly created developers, where neither toner particles nor carrier particles have traditionally been used in the development process, are particularly useful in the early cycles of their use in electrophotographic development processes (often
The developer exhibits various disadvantages during its initial life (referred to as the initial life of the developer).

For example, within the first 2.3 minutes of use (which can involve the development of hundreds of toner images depending on processing speed),
The charge levels on the toner particles and carrier particles of the developer material can change rapidly and dramatically, resulting in wide variations in the degree and quality of development of successive images over time.

We refer to this problem as early life charge fluctuation.

Additionally, throughout its initial life, toner particles and particles that are not properly retained on the surface of the carrier particles, for example, are exposed to the surface of the toner particles, where the developer material adheres (i.e., is not properly retained on the surface of the carrier particles) during agitation of the developer material by typical development devices, such as magnetic roll applicators. The developer may exhibit high levels of undesirable desorption (also referred to as dusting), defined as the amount of particulate matter. High levels of dusting can cause excessive wear and tear on xerographic equipment, contamination of the toner with dirt and carrier materials that result in greater charge fluctuations, contamination of the surrounding air with toner particles and other particulate matter, and other undesirable conditions. may have an impact.

Both the early life charge variation problem and the early life dusting problem are believed to be caused by the physicochemical conditions of the carrier particles and their modification during use in development.

(5) (6) Abrasion of the carrier surface, such as by filling or scattering of pores on the carrier surface by the toner material, by removing dirt or other surface irregularities, or by peeling off the colorant. By chemical modification of the carrier core through reaction with chemical toner components such as charge agents,
By chemical modification of the carrier coating (e.g., polymeric materials known to provide benefits when applied to the carrier core) through reaction with toner components or exfoliated carrier materials or combinations thereof; Contamination of the toner particles with material detaching from the particles and possible chemical reactions between them result in initial life charge fluctuations, all of which can change the triboelectric relationship between the carrier particles and the toner particles.

Initial life dusting is the cause of initial life charge fluctuations (partial peeling off of the carrier material, carrier coating material, or dirt on the carrier surface, contamination of toner particles associated with it, and triboelectrification of the carrier and/or toner particles). (due to denaturation) or as a result of early life charge fluctuations (due to a reduction in the attractive force between carrier and toner due to lowering the early life developer charge level).

Therefore, early life dusting may be caused by any of the same factors that result in early life charge fluctuations, but primarily due to the removal of dirt and other foreign matter from the carrier surface and/or the removal of dirt and other foreign matter from the carrier material (particularly the This may be caused by fragmentation or exfoliation of some of the particles (foreign components or irregularities), and concomitant contamination of the toner particles.

The prior art literature describes a variety of methods for treating developer materials to reduce early life charge fluctuations and other issues. For example, U.S. Pat. No. 4,678,734;
See 3,970,571 and 3,960,738. Although these conventional methods appear to have a beneficial effect on early life charge variation, they do not solve the problem of early life dusting.

(7) (8) [Problem to be Solved by the Invention] The present invention provides a method for using carrier particles not used in conventional developers, which will simultaneously alleviate the problems of initial life charge fluctuation and early life dusting. The object is to solve the above problem by providing a relatively simple method for processing.

[Means for Solving the Problems] The present invention is a method for preconditioning carrier particles prior to their first use in a dry electrophotographic developer comprising a mixture of carrier particles and toner particles, comprising: A. a carrier; forming a mixture of particles and preconditioned particles, each preconditioned particle containing (1) a polymeric binder useful in electrophotographic toners, and (2) controlling the level of triboelectric charging of the electrophotographic toner. B, agitating said mixture of carrier particles and preconditioned particles to promote contact therebetween, and C1 thereafter removing substantially all of said carrier particles from said carrier particles. separating the preconditioned particles of.

The method of this invention can be advantageously applied to all carrier particles known to be useful in electrophotographic developers. Such carrier particles can be made of a variety of materials and can consist of a core particle or a core particle coated with another material, such as, for example, a thin resin film layer.

These carrier cores can include electrically conductive, non-conductive, magnetic or non-magnetic materials. For example, carrier cores such as glass beads, crystals of inorganic salts such as potassium aluminium chloride, ammonium chloride or other salts such as sodium nitrate, granular zircon, granular silicon, silicon dioxide, poly(methyl methacrylate), etc. hard resin particles, metallic materials such as iron, steel, nickel, carborundum, cobalt or iron oxide,
Alternatively, it can be composed of a mixture or alloy (9) (10) of any of the above. For example, U.S. Pat.
See No. 50.663 and No. 3,970.571. Particularly useful in magnetic brush development systems are porous iron particles with oxidized surfaces, steel particles, and gamma ferric oxides or ferrites (e.g. barium ferrite, strontium ferrite, lead ferrite, magnesium ferrite or aluminum ferrite). For example, U.S. Pat. Nos. 4,042,518 and 4,478,9
No. 25, No. 4,546,060 and No. 4,764,
See specification No. 445.

Carrier particles such as those described above can be coated with a thin layer of film-forming resin to establish the proper triboelectric relationship and charge level with the toner used.

Examples of suitable resins include U.S. Pat. No. 3,547,822;
These are polymers described in Belgian Patent No. 3,632,512, No. 3,795,618 and No. 3,898,170 and Belgian Patent No. 787,132. Other useful resins are fluorocarbons such as polytetrafluoroethylene, poly(vinylidene fluoride), mixtures thereof, and copolymers of vinylidene fluoride and tetrafluoroethylene.

For example, U.S. Patent Nos. 4,546,060 and 4,47
No. 8,925, No. 4,076.867 and No. 3,9
See No. 70,571. Such polymeric carrier coatings can serve a number of known purposes. One such purpose is to adjust the degree of triboelectric charge of both the carrier particles and the toner particles by moving the carrier particles from an uncoated core position to a different triboelectric system position. This can be useful in making the developer meet the electrostatic force requirements. Another purpose is to be able to reduce the coefficient of friction of the carrier particles to improve developer flow.

Yet another objective is to be able to reduce the surface hardness of the carrier particles so as to reduce their tendency to wear during use. Yet another purpose is
Toner Materials or Other Developers (11) (12) Additives that reduce the tendency of undesirable permanent adhesion to the carrier surface during developer use (often referred to as scabbing). A further objective is to be able to modify the electrical resistance of the carrier particles.

Many methods of applying such coatings in continuous or discontinuous configurations of various uniform or non-uniform thicknesses are well known. Some useful methods include solvent coating, spray coating, plating, tampling, shaking, fluid bed coating, and melt coating. For example, U.S. Patent No. 4,546,0
No. 60, No. 4,478,925 and No. 4,233,
See specification No. 387. In a particular embodiment of this invention, illustrated in the examples below, the coating is discontinuous and comprises poly(vinylidene fluoride) melt applied onto a carrier core.

These carrier particles can be spherical or irregularly shaped, smooth or rough-surfaced, and of any size known to be useful as a developer. good. Generally, suitable carrier particles have an average particle size within the range of 2 to 1200 marks.

Each preconditioned particle used in the method of this invention comprises a mixture of a polymeric binder and a charging agent.

The polymeric binder includes all polymeric materials that may be useful as binders for electrophotographic toners, many of which are known.

Useful polymers are thermoplastics with glass transition temperatures within the range of 40°C to 150°C. The polymer may be a homopolymer or a copolymer, and may include a single polymer or a blend of polymers. Some useful types of polymers include:
polyesters (also including polycarbonates),
Included are polyamides, phenol-formaldehyde polymers, bonaester amide resins, alkyd resins and vinyl etch polymers (typically those made from styrene, butadiene, acrylates and methacrylates, etc.). Some further descriptions of useful representative poly(13)(14) Limerhinders are found, for example, in U.S. Pat. No. 4,812,377;
No. 2, No. 4,217,440, No. 4,140,644
No. 3,694,359, No. 4,601,966, No. 3,809,554, Reissue No. 3L072,
U.S. Patent Nos. 2,917,460 and 2,788,28
No. 8, No. 2,638,416, No. 2,618,552
No. 4,416,965, No. 4,69L966 and No. 2,659,670. Some specific examples of polymers useful in the preconditioned particles of the methods of this invention include poly(styrene-coptyl acrylate), poly(styrene-coptyl methacrylate), and poly(propylene-coglyceryl terephthalate-coglutarate). ).

Charge agents useful in these preconditioned particles include any materials that, when incorporated into or combined with them, may be useful in achieving or controlling a particular level of triboelectric charge of the electrophotographic toner particles. is included. Many such charge agents are well known and include non-polymeric and polymeric materials. Some of these polymeric materials can function as both binder and charge agent simultaneously. Some of the useful types of charge agents are aromatic and aliphatic quaternary ammonium and phosphonium salts, both polymeric and non-polymeric, primary, secondary and tertiary amines, metal complex dyes, and naphthalene sulfonic acids. It is an acidic organic molecule such as. Further details on some representative charge agents can be found at
For example, U.S. Patent Nos. 3,893,935 and 4,07
No. 9,014, No. 4.323,634, No. 4,394
, No. 430, No. 4,496,643, No. 4,547,
No. 449, No. 4,684,596, No. 4.83739
No. 1, No. 4,837,392, No. 4,837,393
No. 4,837,394, No. 4,812,378, No. 4,812,382, No. 4,789,614,
See 4,812,380, 4,840,864 and 4,812,381. Some specific examples of charge agents useful in the preconditioned particles of the method of this invention include benzyldimethyloctadecylammonium chloride, methyltriphenylphosphonium p-
) luenesulfonate, (15) (16) (3-lauramidopropyl)trimethylammonium methylsulfonate and benzyldimethyloctadecyl ammonium 3-nitrobenzenesulfonate.

The optimum ratio of binder and charge agent to be included in the preconditioned particles will vary depending on the nature of all materials involved and the length of time spent in the stirring step. However, some of each must be present,
Generally, the optimum amount of charge agent is 1,000 i based on the total weight of the adjusted particles.
~4% by weight. In some embodiments, when the particles are milled to a predetermined size, the final preconditioned particles have a higher concentration of charge agent on their surface than on the inside;
The binder and charge agent will be in separate phases within the preconditioned particles so that rupture occurs preferentially in the charge agent phase. This appears to provide a more significant effect in reducing early life charge fluctuations. An example of a preconditioned particle that exhibits this phase separation is where the charge agent is a phosphonium salt such as methyltriphenylphosphonium p-)luenesulfonate and the binder is a vinyl addition polymer such as poly(styrene-coptyl acrylate). include something.

These preconditioned particles can be prepared by any conventional method known for making toner particles (e.g., U.S. Pat. No. 4,684,
596 and 4,394,430) by dispersing a charging agent in a polymer binder. This mixture is then ground to a predetermined size to form a free-flowing powder of preconditioned particles. The size of the particles is not critical, but extremely small particles may make separation from the carrier particles more difficult after the agitation step of this method. In a particular embodiment of the method of the present invention, the average pre-mm size particle size is in the range of 11 to 14n, and there are very few particles with less than 5 to 6 sides.

In practicing the method of this invention, these preconditioned particles are simply mixed with sufficient carrier particles to maximize the surface area of the carrier particles that are contacted with the preconditioned particles. This amount (17) (18) will vary depending on the relative size and density of the preconditioned particles and carrier particles. In certain embodiments of the invention, the preconditioned particles represent 10-13% by weight of the mixture.

The mixture is then agitated by any convenient means to promote contact between the preconditioned particles and the carrier particles. The length of stirring time required for best results will depend on the intensity of stirring and the nature of the materials involved. In certain embodiments, best results are achieved by stirring for 0.1 to 6 hours.

After this agitation step is completed, substantially all of the preconditioned particles are separated from the carrier particles by any convenient means and then discarded.

If these preconditioned particles and carrier particles occupy distinctly separate positions in the triboelectric continuum, then through the agitation process they will acquire a triboelectric charge and the preconditioned particles will be of one polarity. A charge is captured, and the carrier particles capture a charge of opposite polarity. In this case, for example, one of the electrode plates is grounded and the other is charged with a polarity opposite to its charge so that the preconditioned particles adhere to it while the carrier particles are repelled by the electrode plate. Separation can conveniently be effected electrostatically by passing the mixture between plates. In certain embodiments of the process of this invention, nearly complete separation was achieved by the process (i.e., 97% by weight of the preconditioned material).
~99.9% or more by weight separated from carrier particles).

In other cases, for example when the dimensions of the preconditioned particles differ significantly from those of the carrier particles, separation can be conveniently achieved by other means, such as sieving with air agitation.

After separation, these carrier particles are then used in well-known dry electroscopic development systems such as cascade development or magnetic brush development, which would otherwise occur if the carrier particles were not subjected to the preconditioning method of the present invention. The toner is subjected to conditions of admixture with any of the toner (19) (20) particles suitable for forming an electrophotographic developer that can exhibit significantly reduced initial life charge fluctuation and early life dusting than the toner particles.

〔Example〕

The following examples further illustrate certain embodiments of the preconditioning method of the present invention and demonstrate the beneficial effects of this method on carrier particles when no such preconditioning was performed or when no such preconditioning was performed. This is provided for the purpose of specifically explaining the comparison with carrier particles prepared in a manner other than the invention.

In all of the following examples, the carrier particles consisted of a strontium ferrite core melt-coated with poly(vinylidene fluoride). They were made using a formulation comprising 1-2% by weight of poly(vinylidene fluoride) and 98-99% by weight of strontium ferrite particles. 2 kg of this product was placed in a 4C wide mouth glass jar and covered. The jar was manually shaken vigorously and then rolled for 15 minutes at 140 revolutions per minute. The lid was then removed and placed in a convection oven set at a temperature of 230'C for 4 hours. After cooling to room temperature, the coating was passed through a 62-hole sieve to break up any large agglomerates.

In these examples, typical toner particles are mixed with carrier particles to create a charged electrophotographic developer containing 13% toner by weight, and the toner 1 before a test run of this developer.
measuring the charge level present on the toner particles in microcoulombs per gram (μc/g); measuring the charge level on the toner after 5 minutes of continuous test run of the developer;
Next, the degree of initial life charge fluctuation was measured by the change in charge level obtained by subtracting the value of the latter charge level from the former (! (This is a typical example of the degree of initial life charge fluctuation).The continuous test operation of this developer was , involves placing that developer in a glass bottle fixed in place on top of a typical apparatus designed to align the developer with an agitating magnetic brush for development of an electrostatic image into a toner image (this case,
Cylindrical rolls with rotating magnetic cores). This continuous test run therefore closely approximates the typical real-life early life use of a developer in an electrophotographic process.

(21) (22) In these examples, for the purpose of measuring toner charge and health, the degree of initial life charge fluctuation of the developer containing carrier particles subjected to the preconditioning treatment of the present invention is measured by the treatment of the present invention. Any known suitable method for measuring 1-ner charge levels is intended only to contrast the degree of initial life charge variation of similar developers containing unattached carriers. methods can also be used. On each side of the following, a 0.05-081 g portion of charged developer is placed in a sample pan placed between the electrode plates, and then a magnetic field of 60) Iz is applied between the electrode plates to cause agitation of the developer. The toner charge level was determined by simultaneously applying an electric field of approximately 2000 volts per cm for 30 seconds. This toner is released from the carrier and then attracted and collected onto an electrode plate having an opposite polarity to the toner charge. The total toner charge is measured with an electrometer connected to the plate, and the value is divided by the weight of toner on the electrode plate to give 1g.
The charge per amount of toner is given as microcoulombs per unit (μc/g).

In these examples, typical toner particles are mixed with carrier particles to create a charged developer comprising 12% toner by weight, the developer is agitated for about 10 minutes, and the same type of toner particles are mixed with the same type of toner particles as previously described. A representative developer is further mixed with a developer to produce a charged developer comprising 18% by weight of toner and designed to align the developer with an agitating magnetic brush for development of the electrostatic latent image into a toner image. The developer is placed in an open container fixed in place at the top of the device (in this case the cylindrical roll is accompanied by a rotating magnetic core), and a weighed piece of fiberglass filter paper and a vacuum hose connected to its spout are placed. Place the containing funnel upside down on the open container, simultaneously rotate the magnetic core for 1 minute to form a stirred magnetic developer brush similar to a normal development process, and remove all of the stirred magnetic developer brushes. Apply a vacuum to the funnel to collect the material on the filter paper, weigh the filter paper and the collected material, and then subtract the weight of the filter paper from the combined weight to obtain the initial life dusting in milligrams (■). The degree of initial life hulling (desorption) (23) (24) was determined by measuring at .

In Examples 1 to 6, the carrier particles were comprised of 98% by weight strontium ferrite core material and 2% by weight poly(vinylidene fluoride) resin coating. In Control A, the carrier particles were not subjected to any preconditioning treatment. Examples 1-6
The carrier particles in form a mixture comprising 87% by weight of carrier particles and 13% by weight of preconditioned particles;
The mixture was preconditioned according to the present invention by stirring the mixture for 0 minutes and then electrostatically separating substantially all (97-99.9% by weight) of the preconditioning material from the carrier particles. Next, all of these carrier particles were mixed with toner particles to prepare an electrophotographic developer, and then the initial life charge fluctuation degree and initial life dusting degree were determined as described above. These toner particles in all cases included a quaternary ammonium salt charge agent, a polymeric siloxane release agent, a yellow colorant, and a split amorphous polyester binder.

In Examples 1-6, the preconditioned particles were 11-16I! II
The particles had an average particle size within the range of 1.1 and consisted of 98% by weight of polymer binder and 2% by weight of charge agent.

The polymeric binder of the preconditioned particles in Examples 1-3 was manufactured under the trademark Piccotoner 127B.
cules co.

Poly(styrene-coptyl acrylate) (80:20) commercially available from (USA). Examples 4-6
The polymeric binder of the preconditioned particles in was a branched amorphous polyester in which the repeating units were derived from terephthalic acid, geltaric acid, propanediol and glycerol with a molar ratio of 87:13:95:5, respectively. The charge agent of the pre(Ilf-adjusted particles in Examples 1 and 4 is benzyldimethyloctadecylammonium chloride, that of Examples 2 and 5 is methyltriphenylphosphonium P-)luenesulfonate, and that of Examples 3 and 6 is benzyldimethyloctadecylammonium chloride. It was tatecylammonium 3-nitrohenzene sulfonate.

The results are shown in Table 1.

(25) (26) Table 1 Control A 36.5 11.4
25.11 33.7 1
6.4 17.32 15.9
11.3 4.63
28.8 14.3 14.5
4 40.4 21.5
18.95 34.1
21.5 12.66 41.6
22.1 19.5 The results in Table 1 show that in all cases the preconditioning treatment of the present invention of the carrier particles shows the initial life charge variation and initial life powder of the developer after it has been made with the treated carrier particles. A distant relative was found in the case consisting of a binder (Example 2) and a methyltriphenylphosphonium p=toluenesulfonate fE loading agent (Example 2), which was shown to significantly reduce oxidation.

In Examples 7 and 8, preliminary preparation of the carrier and developer test were carried out.
It was carried out exactly as in Examples 2 and 5, respectively. Control B
and Examples 7 and 8 only differed in that they contained 99% by weight strontium ferrite core (instead of 98%) and 1% by weight poly(vinylidene fluoride) resin coating (instead of 2%). Control B received no preconditioning treatment. The results are shown in Table ■.

Control B 35.1 8
27.1 115.87 11.4
7.6 3.8
0.5B 30.9 15
．． 2 15.7 0.5 units 1 In Example 9, the carrier particles and inventive preconditioning are exactly the same as in Example 2. The developer test was also the same as Example 2, except that the toner particles contained magenta colorant instead of yellow colorant. Pairs (27) and (28) In case C, no preliminary adjustment process was performed. See the results
Shown in the table.

Control C7340,333,00,3 929,224,25,00,4 The carrier particles and inventive preconditioning treatment in Example 10 was exactly the same as in Example 7. The developer test was also the same as Example 7 except that the toner particles contained magenta colorant instead of yellow colorant.

The control sample was not subjected to any preconditioning treatment. See the results
Shown in the table.

Control D 67.9 32.9
35.010 21.2 16.
1 5.1 The carrier particles and inventive preconditioning treatment in Example 11 was exactly the same as in Example 2. The developer test was also the same as Example 2 except that the toner particles contained cyan colorant instead of yellow colorant.

Control E received no preconditioning treatment. Results in Part V
Shown in the table.

Control E 41.5 14.2
27.3 36.711 1B, 4
14.1 4.3 0
．． The carrier particle and developer tests in 8 quarts 1 stitch Examples 12-15 were exactly the same as in Example 2. The inventive preconditioning process was the same as Example 2 with two exceptions. The stirring step of the method of this invention is
15 minutes instead of 30 minutes were run, and the preconditioned particles had different binder to charge agent ratios. Example 12,
The preconditioned particles in Nos. 13, 14, and 15 contained 99% by weight, 98% by weight, 97% by weight, and 96% by weight of binder, and 1% by weight, 2% by weight, and 3% by weight of charge agent, respectively. and 4% by weight at the bottom of the tank. Control F received no preconditioning treatment. Control G
carried out the same preconditioning treatment as in Examples 12 to 15, but differed from this invention in that the fN adjustment particles consisted of 100% binder and did not contain any charge agent. The results are shown in Table 1. The control G treatment had the advantageous effect of reducing initial life charge fluctuations, but the initial life dusting was significantly worse.

Control F 36.5 Control G 19.3 12 22.7 13 17.6 14 12.7 15 8.6 11.4 25.1 7.6 11.7 15.2 7.5 12.3 5.3 9.2 3.5 5.4 3.2 24.0 62.7 0.6 0.4 0.4 1.4 [Effects of the Invention] The method of this invention is characterized in that carrier particles are mixed with toner particles. When subsequently making electrophotographic developers, the carrier particles are unexpectedly and beneficially improved as the developers exhibit a significant reduction in early life charge fluctuation and early life dusting during their use.

Although the mechanistic reasons for this combined beneficial effect are unknown, a significant reduction in early life dusting is due to the portion of this invention that clearly differs from the conventional methods described in the three aforementioned U.S. patents. Special mention is made of what has been clearly achieved.

That is, the method of the present invention involves substantially complete separation of the former from the latter after agitated contact of the carrier particles and the preconditioned particles, whereas the method of the present invention involves substantially complete separation of the former from the latter after agitated contact of the carrier particles with the preconditioned particles; No. 4,678,734 and No. 3,970,571), or no significant reduction (see U.S. Pat. (U.S. Pat. No. 3,960,7)
No. 38). (31) (32) Due to the fact that dirt and other foreign matter from the carrier surface, and also any carrier particle material that has been abraded or fractured from the carrier, is incorporated into the preconditioned particles and, if not, becomes integral with the particles. Thus, substantially complete separation of preconditioned particles from carrier particles by the method of the present invention results in early life powders because these materials are carried away from the carrier particles along with the preconditioned particles through the separation process. It is presumed that it reduces standing.

The conventional method actually uses developer (comprising toner particles and carrier particles) rather than carrier particles.
This is a method for processing and modifying. All these methods involve the use of a toner material having the same chemical composition as the final developer produced for it as "conditioned" particles. Their intent is to create the final developer and to modify the properties of both the toner particles and the carrier particles in the developer, rather than to act strictly on the carrier particles; There is no suggestion that the carrier particles in a developer can or will be substantially completely separated from the toner particles of that developer thereafter. In fact, the methods taught by the prior art are intended for the scumming of the surface of the carrier and the filling of the carrier pores with toner materials, as well as for the modification of the toner particles, for example with respect to their particle size distribution. Subsequent attempts to completely separate the carrier particles from the toner particles prior to mixing the carrier particles with other toner particles for use in de facto development would be diametrically opposed to the purpose of these methods, and
And it's not suggested anywhere.

Furthermore, in certain embodiments of the methods of the present invention, the preconditioned particles are substantially free of colorant and can therefore be used with preconditioned carrier particles, such that the toner particles are colorless or have a special hue. It would have the advantage of being able to subsequently use them in a developer containing any toner particles, regardless of whether they have . Although the intent of the method of this invention is to separate substantially all of the preconditioning process from the carrier particles, the stirring process (3
3) (34) Significant extra effort may be required (or in some cases may not be possible). If pigments are present in the preconditioned particles, even traces of such pigments remaining on the carrier particles after the method of this invention may be of a different hue from that of the pigments in those preconditioned particles. It will often be sufficient to undesirably alter the hue of a developer made by mixing dye-containing i-ner particles with preconditioned carrier particles. This is an example of the method specifically described in the three prior art US patents mentioned above. That is, in these methods pigments are included in the conditioning step and therefore these carrier particles cannot be subsequently used with any toner particles other than those having the same hue as the pigments included in the conditioning step. Make it appropriate.

(35)

Claims (1)

[Claims] 1. A method for preconditioning carrier particles prior to the first use of the carrier particles in a dry electrophotographic developer comprising a mixture of carrier particles and toner particles, comprising: A. carrier particles and preconditioning; forming a mixture with particles, each preconditioned particle containing (1) a polymeric binder useful in an electrophotographic toner and (2) a charge useful for controlling the triboelectric charge level of the electrophotographic toner. B. agitating said mixture of carrier particles and preconditioned particles to promote contact therebetween; and C. thereafter removing substantially all said preconditioned particles from said carrier particles. A method comprising the step of separating.